W124 code READER
Newbie
Joined: Oct 2020
Posts: 7
Likes: 2
1993 Mercedes 300ce-24 Cabriolet
W124 code Reader mot getting any codes
Hello, I made a code Reader that blinks, but when I try to Read the codes I don't get anything it just lights up when I press the button but nothing after or occasionally s very faint light or flashing that's not helpful. I'm trying to read the soft top codes is there another way? Or just from the 16 pin connector near the battery? It's a 1993 300 ce 24 cabrio. THANKS!
Newbie
Joined: Nov 2010
Posts: 11
Likes: 3
300e
Why does the LED light immediately turn on when I plug in?
A typical issue on these older Mercedes. The LED immediately turning ON or dimly means the system/circuit you're testing has a closed fault due to a stuck relay, solenoid, corrosion on contacts or even spider webs allowing phantom voltage to pass. Finding the faulty part(s) is a process of elimination. The circuit being closed prevents the code reader from receiving pulse voltage from the car’s diagnostic module. I'd start unplugging relays and whatever else you can jiggle around. Then on to swapping / replacing parts. I always thought Mercedes was stupid designing the OBD1 code system like Christmas tree lights....if one part is fused shut you can't read any codes on that system. And for ports that do respond correctly....... When you press the button and it lights up and release and you get no flashes or one flash that indicates no code is stored on that circuit. And to make sure a code isn't missed you might try holding the button down longer before releasing. My #6 takes like 10 seconds of push/hold to get the codes blinking. Good Luck, Rick.
Please download my PDF fault code file at www.mercedescodereader.com/files.html
A typical issue on these older Mercedes. The LED immediately turning ON or dimly means the system/circuit you're testing has a closed fault due to a stuck relay, solenoid, corrosion on contacts or even spider webs allowing phantom voltage to pass. Finding the faulty part(s) is a process of elimination. The circuit being closed prevents the code reader from receiving pulse voltage from the car’s diagnostic module. I'd start unplugging relays and whatever else you can jiggle around. Then on to swapping / replacing parts. I always thought Mercedes was stupid designing the OBD1 code system like Christmas tree lights....if one part is fused shut you can't read any codes on that system. And for ports that do respond correctly....... When you press the button and it lights up and release and you get no flashes or one flash that indicates no code is stored on that circuit. And to make sure a code isn't missed you might try holding the button down longer before releasing. My #6 takes like 10 seconds of push/hold to get the codes blinking. Good Luck, Rick.
Please download my PDF fault code file at www.mercedescodereader.com/files.html
Last edited by rick dean; Dec 3, 2020 at 09:04 AM. Reason: update
Newbie
Joined: Nov 2010
Posts: 11
Likes: 3
300e
Could be previous owner replaced wiring harness and ignored the OBD1 hookup. You'll need to use the battery for Red power/#16. Looks like #1 has a ground. On the early cars like yours its common to have only 4-6 systems to test. Other than the missing #16 power I don't see any issues. Rick
